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Available to listen.
Last broadcast on Sun, 25 Oct 2009, 14:32 on BBC World Service (see all broadcasts).
Synopsis
In August 1982, a group of plant pathologists published a paper in the Journal of the Hungarian Meteorological Service. The paper was called “The association between bacteria and rain and possible meteorological implications”. The wording was cautious. But more than twenty-five years later, scientists are beginning to find the evidence to show how bacteria could play a dynamic role in our weather.
Scientists have understood for some time that airborne particles can help water to turn to ice. Known as “ice nucleators”, they provide a catalyst for ice formation. What has been less well understood is that bacterial particles can persuade water to freeze at relatively high temperatures, possibly as warm as -10 C.
This is significant because water has to turn to ice before rain can fall. If bacterial particles cause water to freeze at relatively warm temperatures, the water in the clouds will turn to ice more easily. As the ice crystals grow in size and number, they become large enough to start falling. As they fall, they turn back to water and become raindrops.
In this week’s Discovery, Richard Hollingham meets some of the scientists who are working in what has been called “bioprecipitation”. He talks to David Sands from Montana University who coined the term “bioprecipitation”. He also visits labs in Avignon and London where researchers are trying to understand more about the impact of bacterial particles on our weather.
Broadcasts
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Wed 21 Oct 200910:32
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Wed 21 Oct 200916:32
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Wed 21 Oct 200920:32
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Thu 22 Oct 200901:32
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Sun 25 Oct 200914:32
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